Book Image

Raspberry Pi 3 Projects for Java Programmers

By : Rajdeep Chandra, John Sirach, Pradeeka Seneviratne
Book Image

Raspberry Pi 3 Projects for Java Programmers

By: Rajdeep Chandra, John Sirach, Pradeeka Seneviratne

Overview of this book

Raspberry Pi is a small, low cost and yet very powerful development platform. It is used to interact with attached electronics by the use of it's GPIO pins for multiple use cases, mainly Home Automation and Robotics. Our book is a project-based guide that will show you how to utilize the Raspberry Pi's GPIO with Java and how you can leverage this utilization with your knowledge of Java. You will start with installing and setting up the necessary hardware to create a seamless development platform. You will then straightaway start by building a project that will utilize light for presence detection. Next, you will program the application, capable of handling real time data using MQTT and utilize RPC to publish data to Further, you will build a wireless robot on top of the zuma chassis with the Raspberry Pi as the main controller. Lastly, you will end the book with advanced projects that will help you to create a multi-purpose IoT controller along with building a security camera that will perform image capture and recognize faces with the help of notifications. By the end of the book, you will be able to build your own real world usable projects not limited to Home Automation, IoT and/or Robotics utilizing logic, user and web interfaces.
Table of Contents (8 chapters)
Integrating a Real-Time IoT Dashboard

Reading and displaying the values from the LDR

Doing this needs some experimentation on the values we want to have, especially because everyone's definition of It is dark is different. Remember, the longer it takes for the pin to detect the high state, the darker it is.

Close all the tabs except the Main class, where we will be uncommenting the next example to run. Scroll to the main function where we will be commenting the runLcdExample(); and uncomment the runLdrExample(); method. This next method runs the example of how to measure light intensity. When the LDR is connected like in the previous directions, you are able to run the application again by pressing the Run button in the button bar. Take a look at the LCD display where we see different text appearing depending on the light intensity surrounding the LDR.

When there is a lot of light, the display could show information as shown in the following screenshot...